A fan device is widely applied into a cooling apparatus, and is used for dissipating heat of heat generating components such as a vehicle engine. An engine cooling fan used in an existing engine cooling system controls a rotation speed of the fan by regulating resistance. In a motor drive device for controlling the rotation speed of the fan, a relay is used to regulate the resistance value of the resistance, and multiple wire harnesses are used to deliver a control signal between an electronic control unit (ECU) of the vehicle and the relay, which results in increase of cost of the fan.
In another existing way, the rotation speed of the fan is regulated by a pulse width modulation (PWM) regulator. The PWM regulator is connected to the ECU of the vehicle, to change a duty ratio in a real-time manner in response to an instruction of the ECU, so that a voltage outputted to a motor of the fan is regulated, and further the rotation speed of the fan is regulated continually. However, a field effect transistor (Mosfet) is switched at a high frequency for continually regulating the rotation speed of the fan, which results in high power consumption and the significant increase of the cost of the fan, since a large radiator needs to be installed to dissipate heat generated by the power consumption and an expensive microprocessor is required to process diagnosis feedback information on operation of the fan.